Coolant leak (Solution)

If the engine is consuming coolant, the first step is to determine where it's disappearing to. If the oil level is rising due to water contamination, or if oil is present in the coolant, a faulty head gasket or a crack in the cylinder head should be suspected.
If coolant is leaking somewhere, the problem is obviously easier to find, and the goal is to fix the leak.
Sometimes, the engine can overheat "for no reason," meaning without any visible leaks, resulting in a loss of coolant. In such cases, the coolant thermostat in the water pump and the cap of the coolant reservoir should be checked. The cap contains a valve that occasionally fails, which can cause the cooling system to become depressurized when it's hot, leading to the coolant boiling.